The answer is: Difficult to control all variables except one being tested
I know this isnt an exact answer but the easiest way to find this is online you really did not need to ask here but heres the answer any way. <span>Cell wall, chloroplasts, central vacuole.</span>
Answer: B. it went faster as time went on
Answer: C. To see and help the body respond to the environment.
Explanation: Good luck! :D